A variety of clinical circumstances, including massive trauma, major surgical procedures, massive burns, and certain disease states such as pancreatitis and diabetic ketoacidosis can produce profound circulatory volume depletion, either from actual blood loss or from internal fluid imbalance. In these clinical settings, it is frequently necessary to infuse blood or other fluids rapidly into a patient to avert serious consequences.
In the past, the replacement of large amounts of fluids has been a major problem to the medical or surgical teams attending a patient with these acute needs. A common method of rapid infusion involves the simultaneous use of a plurality of infusion sites. Frequently, a plurality of medical personnel are required to establish and oversee the various infusion sites and to personally ensure the flow of fluids from their respective container bags. This method may be limited by the number of peripheral or central sites that can be physically accessed in a given patient, the number of people attending the fluids being infused, as well as the efficiency of infusing the fluids during a dire, hypovolemic event. It is not uncommon for four to five anesthesiologists or technicians to stand in attendance during transplant operations lasting more than twenty-four hours attempting to infuse massive quantities of blood through five or six venous catheters.
Patients who have undergone massive trauma or surgery such as liver transplantations or other elective procedures may require voluminous quantities of fluids to maintain a viable circulatory state. Although it is not uncommon for an anesthesiologist or surgeon in a major trauma and transplantation center to encounter massive exsanguination of ten liters or more, it is unusual to successfully resuscitate a patient with such massive blood volume loss using traditional methods.
While the potential need for rapid infusion is present in a number of common clinical situations, the actual need is unpredictable and may arise suddenly during the course of treatment or surgery. Therefore, it would be advantageous to have a system that could rapidly transition from normal infusion to rapid infusion with minimal operational intervention.
In patients suffering blood loss, measuring the pressure in the large central veins (central venous pressure or C.V.P.), is a good objective method for assessing the efficacy of volume replacement. A low C.V.P. indicates that the patient does not have adequate intravascular volume and thus further fluid resuscitation is necessary. A high C.V.P. is an indication of volume overload and can result in heart failure and pulmonary edema (or fluid) in the lungs. Presently, C.V.P. is most commonly measured by placement of a large catheter in the patient's neck that is connected to a pressure transducer. This transducer converts pressure changes into an electrical signal that is displayed on an oscilloscope-type monitor. Intensive care units and operating rooms are usually the only hospital areas capable of measuring C.V.P. In an emergency department setting, fluid administration is gauged empirically using mainly the patient's blood pressure and pulse to assess the adequacy of volume replacement.
Rapid infusion devices are best used while monitoring C.V.P. The volume and rate of flow into the patient can then be quickly and accurately adjusted to sustain an adequate C.V.P., lessening the chances of complications of heart failure and pulmonary edema from fluid overload.
The prior art contains a number of devices and methods that have attempted to address the clinical need for rapid intravenous fluid infusion.
U.S. Pat. No. 5,840,068 to Cartledge discloses a device and method for the rapid delivery of an infusion of blood and/or volume expanding fluid to a patient. The device includes a pump system that interfaces with a fluid housing system.
U.S. Pat. No. 5,061,241 to Stephens, et al. discloses a rapid infusion device capable of high volume pumping. The device includes a permanent unit that includes a base portion that houses an AC/DC motor, a roller pump, and other associated gauges and switches. A disposable unit includes a fluid housing, heat exchange component, and associated tubing leading to the roller pump. The roller pump increases the volume of fluid being pumped by increasing the r.p.m. of the pumping unit and includes a pressure control valve.
U.S. Pat. No. 4,747,826 to Sassano discloses a portable infusion system consisting of supply sources, fluid housings, and associated tubes and valves leading to an infusion pump which can be a centrifugal or a roller head occlusive pump.
U.S. Pat. No. 4,187,057 and U.S. Pat. No. 4,537,561 to Xanthopoulos disclose peristaltic infusion pumps employing disposable cassettes to house the infused fluid. In the '057 patent, the fluid conduit is held in the cassette in an arcuate configuration for its active interface with a pump rotor assembly. In the '561 patent, the fluid conduit is held in the cassette in a linear configuration for its active interface with a pump rotor assembly. It appears that the pumps can provide only routine infusion rates.
U.S. Pat. No. 4,410,322, to Archibald discloses an intravenous infusion pump that employs a piston-cylinder pump and a disposable pump chamber. The pump chamber contains a linear series of diaphragm enclosures that propel the infused fluid from the action of the pump cycles. Dielectrical sensors are employed to detect the presence of air bubbles in the disposable pump chamber. When air is detected by the system, an alarm is sounded for operator intervention.
Intravenous infusion rates may be defined as either routine, generally up to 999 cubic centimeters per hour (cc/hr), or rapid, generally between about 999 cc/hr and 90,000 cc/hr (1.5 liters per minute) or higher. Most prior art infusion pumps are designed for medication delivery and are limited in their performance to the routine range of infusion rates. Such pumps are not capable of rapid intravenous infusion. Although some prior art infusion systems can deliver rapid infusion, those prior art rapid infusion devices are physically large, complex systems that require dedicated operation by skilled technicians.
Accordingly, what is needed is a device for rapid infusion that is compact and easily operated by conventional medical personnel in the course of their other duties. What is also needed is a low to high speed infusion device that utilizes a sterile, disposable fluid containment system that can be readily attached and removed from a separate pump system.